[Tutor] lambda

bob gailer bgailer at gmail.com
Sat Mar 19 16:08:39 CET 2011

On 3/19/2011 9:44 AM, Ajit Deshpande wrote:
> I am trying to figure out where lambda functions can be useful. Has 
> anyone used them in real world?
> From my reading so far, I hear people claim that lambda can be a 
> useful replacement for small functions. Most examples  didn't make 
> much sense to me. Why would anyone use a one liner anonymous function, 
> if you never plan to use it elsewhere? You would then be implementing 
> the logic directly in the line, isn't it?. Functions are useful if 
> they plan to get called multiple times within your code.
> For example:
> add_one = lambda x: x + 1
> In real world, why would I use a lambda for this. I would simply do:
> add_one = x + 1
> Can you provide some useful use cases for lambda functions?

One is the list sort method.

someList.sort([cmp[, key[, reverse]]])

/"cmp/ specifies a custom comparison function of two arguments (list 
items) which should return a negative, zero or positive number depending 
on whether the first argument is considered smaller than, equal to, or 
larger than the second argument: cmp=lambda x,y: cmp(x.lower(), y.lower())."

Bob Gailer
Chapel Hill NC

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